The present invention relates to a paper handling apparatus for use with a copier, printer or similar equipment.
Paper sheets driven out of a copier or a printer, for example, have customarily been stacked on individual bins of a sorter or stacker. The stacks of paper sheets are removed from the bins one by one and then bound together by a stapler, punched and then fastened, or bound together by paste. However, picking up the paper stacks one by one out of the bins for binding or otherwise treating them is troublesome and not efficient. A recent achievement in the realm of equipment of the kind described is a paper handling apparatus capable of stapling or otherwise handling paper stacks within bins thereof and, in this sense, sometimes referred to as a sorter and stapler. Typical of this type of paper handling apparatuses is an apparatus which distributes a predetermined number of paper sheets to each of all of the bins and then staple the paper sheets bin by bin, as disclosed in Japanese Patent Laid-Open Publication (Kokai) Nos. 62-290655, 63-60871, and 63-116168. A copier with such a sorter and stapler is generally provided with a function of positioning the paper sheets distributed to the bins. Should the paper sheets be not positioned or neatly arranged on the individual bins, the stapler would fail to bind them neatly. To promote efficient stapling, an arrangement may be made such that as soon as a paper sheet associated with the last document enters the first bin, a stapling operation begins at the first bin without awaiting the delivery of a predetermined number of paper sheets to all of the bins.
Also known in the art is a paper handling apparatus with a so-called dual sort type sorter which has first and second sorter means for distributing paper sheets driven out of equipment body to a plurality of bins. This kind of apparatus is capable of sorting paper sheets of different sizes. A problem with such an apparatus is that providing dual paper positioning means in association with the dual sorter means results in a complicated construction and an increase in cost. It has been customary, therefore, to position paper sheets on all of the bins at a time. This, however, prevents paper sheets of different sizes to be positioned at the same time. Of course, stapling a stack of paper sheets which are not neatly arranged does not make any sense.
A dual sort and staple mode is available with the above-stated prior art apparatus. In such a mode, a plurality of bins are divided into two blocks, and paper sheets distributed to the individual blocks are sorted and stapled endlessly. A problem particular to this mode is that paper stacks on the bins belonging to the first block are dislocated by the operation of stapling means and in turn prevent paper stacks distributed to the second block from being accurately positioned.
With the prior art stated above, efficient manipulations are not achievable because paper sheets of different sizes cannot be sorted in the dual mode.
Further, assume that the copier has run out of paper sheets before the delivery of copies of the last document to all of the predetermined bins. Then, the prior art apparatus staples paper stacks up to the bin to which a copy of the last document was delivered last and, after the supply of paper sheets to the copier, resumes the stapling operation. Since paper sheets are necessarily positioned before stapling, the paper sheets having been stapled before the supply of paper sheets are also positioned. This brings about a problem that since the stapled paper stacks are dislocated on the individual bins, an increase in the number of bins directly translates into an increase in the load acting on a motor which drives the paper positioning device, resulting in the need for a motor having a great torque. Such a motor is not only expensive but also bulky and is, therefore, disadvantageous from the space factor standpoint.